That's the formula which Wendler uses in his 5/3/1 ebook. It's been the most accurate out of any that I've previously used.

So that calculator must use that formula..because I just did the math using (135x10= 1350 x .0333 = 44.95 + 135 = 179.95 I just did 225 10 days ago, so that formula must not work for everyone.. strange...